Characterization of changes in the viscosity of lipid membranes with the molecular rotor FCVJ

Nipper, Matthew E.; Majd, Sheereen; Mayer, Michael; Lee, James C.-M.; Theodorakis, Emmanuel A.; Haidekker, Mark A.

doi:10.1016/j.bbamem.2008.01.005

Cited by 69 publications

(71 citation statements)

References 40 publications

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“…It is important to note that the nature of the viscosity in membranes as measured by molecular rotors is not as straightforward as for bulk samples. At present the precise correlation to conventional measures (i.e., shear or dilatational) of membrane viscosity is not entirely clear (17). The range of action of the molecular rotor is such that the lengthscale on which the viscosity is measured is that of the molecule itself.…”

Section: Methodsmentioning

confidence: 99%

Mapping microbubble viscosity using fluorescence lifetime imaging of molecular rotors

Hosny

Mohamedi

Rademeyer

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

140

114

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Encapsulated microbubbles are well established as highly effective contrast agents for ultrasound imaging. There remain, however, some significant challenges to fully realize the potential of microbubbles in advanced applications such as perfusion mapping, targeted drug delivery, and gene therapy. A key requirement is accurate characterization of the viscoelastic surface properties of the microbubbles, but methods for independent, nondestructive quantification and mapping of these properties are currently lacking. We present here a strategy for performing these measurements that uses a small fluorophore termed a "molecular rotor" embedded in the microbubble surface, whose fluorescence lifetime is directly related to the viscosity of its surroundings. We apply fluorescence lifetime imaging to show that shell viscosities vary widely across the population of the microbubbles and are influenced by the shell composition and the manufacturing process. We also demonstrate that heterogeneous viscosity distributions exist within individual microbubble shells even with a single surfactant component.

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Section: Methodsmentioning

confidence: 99%

Mapping microbubble viscosity using fluorescence lifetime imaging of molecular rotors

Hosny

Mohamedi

Rademeyer

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

140

114

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“…chain to make the farnesyl ester (2-carboxy-2-cyanovinyl)-julolidine (FCVJ) allowed for measurements of fluorescence intensity in model membranes during viscosity changes, [35] but again this intensity-based approach does not take into account the possible changes due to probe concentration.…”

Section: Introductionmentioning

confidence: 99%

Fluorescence Anisotropy of Molecular Rotors

et al. 2011

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We present polarization-resolved fluorescence measurements of fluorescent molecular rotors 9-(2-carboxy-2-cyanovinyl)julolidine (CCVJ), 9-(2,2-dicyanovinyl)julolidine (DCVJ), and a meso-substituted boron dipyrromethene (BODIPY-C(12)). The photophysical properties of these molecules are highly dependent on the viscosity of the surrounding solvent. The relationship between their quantum yields and the viscosity of the surrounding medium is given by an equation first described and presented by Förster and Hoffmann and can be used to determine the microviscosity of the environment around a fluorophore. Herein we evaluate the applicability of molecular rotors as probes of apparent viscosity on a microscopic scale based on their viscosity dependent fluorescence depolarization. We develop a theoretical framework, combining the Förster-Hoffmann equation with the Perrin equation and compare the dynamic ranges and usable working regimes for these dyes in terms of utilising fluorescence anisotropy as a measure of viscosity. We present polarization-resolved fluorescence spectra and steady-state fluorescence anisotropy imaging data for measurements of intracellular viscosity. We find that the dynamic range for fluorescence anisotropy for CCVJ and DCVJ is significantly lower than that of BODIPY-C(12) in the viscosity range 0.6<η<600 cP. Moreover, using steady-state anisotropy measurements to probe microviscosity in the low (<3 cP) viscosity regime, the molecular rotors can offer a better dynamic range in anisotropy compared with a rigid dye as a probe of microviscosity, and a higher total working dynamic range in terms of viscosity.

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“…AA, LPC, PA, phorbol 12-myristate 13-acetate (PMA), DMSO, all-trans retinoic acid, and poly-L -lysine were from SigmaAldrich (St. Louis, MO). Farnesyl-(2-carboxy-2-cyanovinyl)-julolidine (FCVJ) was from Dr. Haidekker's Laboratory (Univerisity of Georgia) ( 30 ).…”

Section: Chemicals and Reagentsmentioning

confidence: 99%

“…A higher fl uorescent intensity of FCVJ refl ects the intramolecular rotational motions being restricted by a smaller local free volume, indicating a more viscous membrane. Previously, we verifi ed the application of FCVJ for measuring membrane viscosity by comparing the results obtained using FCVJ with those from the technique of fl uorescence recovery after photobleaching ( 30 ). In this study, we adapted the protocol from Haidekker et al ( 32 ) to fl uorescently label cells with FCVJ.…”

mentioning

confidence: 99%

Secretory phospholipase A2 type III enhances α-secretase-dependent amyloid precursor protein processing through alterations in membrane fluidity

Yang

Sheng

et al. 2010

Journal of Lipid Research

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The senile plaque composed of neurotoxic amyloid-␤ peptide (A ␤ ) is a pathologic characteristic of Alzheimer's disease (AD) ( 1-6 ). In the amyloidogenic pathway, A ␤ is derived from a proteolytic process of amyloid precursor protein (APP), in which APP is cleaved sequentially by ␤ -and ␥ -secretases ( 7 ). Alternatively, the non-amyloidogenic pathway is mediated by ␣ -secretase, which cleaves between amino acids 16 and 17 within the A ␤ domain. This secretase is a member of the ADAM (a disintegrin and metalloprotease) family and produces a soluble fragment of APP generally regarded as ␣ -secretase-cleaved soluble APP (sAPP ␣ ) ( 8, 9 ). Due to the neurotrophic and neuroprotective properties of sAPP ␣ ( 10 ), increasing the APP processing by ␣ -secretase has been suggested as a new strategy for the treatment of AD ( 11 ).APP is a transmembrane protein, and recent studies show that APP processing can be affected by the local membrane environment. The activity of ␤ -site APP cleaving enzyme (BACE) to produce neurotoxic A ␤ is favorable in lipid rafts, which are highly ordered membrane microdomains enriched in cholesterol, sphingolipids, and saturated phospholipids ( 12-17 ). On the other hand, cleavage of APP by ␣ -secretases is known to occur mainly in nonraft domains ( 18 ). Therefore, APP processing can be altered

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Characterization of changes in the viscosity of lipid membranes with the molecular rotor FCVJ

Cited by 69 publications

References 40 publications

Mapping microbubble viscosity using fluorescence lifetime imaging of molecular rotors

Mapping microbubble viscosity using fluorescence lifetime imaging of molecular rotors

Fluorescence Anisotropy of Molecular Rotors

Secretory phospholipase A2 type III enhances α-secretase-dependent amyloid precursor protein processing through alterations in membrane fluidity

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